1. Field of the Invention
This invention relates to a backlight module, and particularly to a backlight module that is easy for sequential procedures, including assembly, quality examination and disassembly.
2. Description of the Prior Art
Generally, a backlight module refers to a device member capable of providing a light source from the back of a product, which has been widely used in various products related to information, communication and consumer goods, such as liquid crystal displays (LCD), film scanners, slide projectors and so on. The backlight module mainly includes an incident light source, a light-guide plate, a diffusion sheet, a prism sheet and a brightness enhancement film (BEF). Put simply, its principle is that a self- luminous light from a light source, for example, a cold cathode fluorescent lamp (CCFL) and a lighting diode (LED), is conducted in by a light-guide plate to produce an even surface light source. Meanwhile, to keep the products competitive in future markets, the backlight module needs to take several product evolution directions into account: lighter weight, miniaturization, lower power consumption, higher brightness and lower cost.
Reference is made to FIG. 1, which is an assembly diagram of a conventional backlight module 1a. The module 1a includes an upper frame 10a and a lower frame 11a, which are engaged with each other and form a receiving cavity therebetween, and further a light-guide plate 12a, lighting member 13a, a reflective sheet 14a, at least one diffusion sheet 15a and at least one prism sheet 16a, all of which are received within the receiving cavity. The semi-finished module will be further coupled with a glass substrate 2a. The upper frame 10a is provided with a perimetric stop base 101a that is arranged to protrude inward along the inner perimeter at the top side of the frame 10a. During assembly of the module, the upper frame 10a is upside down with respect to FIG. 1, while the perimetric stop base 101a is located beneath the upper frame 10a. According to the design requirement, the diffusion sheet 15a and the prism sheet 16a are placed in order on the perimetric stop base 101a. After the light-guide plate 12a and the lighting member 13a are mounted, the reflective sheet 14a is laid on the light-guide plate 12a. The lower frame 11a and the upper frame 10a are then engaged for the purpose of securing the light-guide plate 12a and the lighting member 13a. At this time, the semi-finished product is roughly assembled. The semi-finished product is then put upside down, such that the perimetric stop base 101a is located above the light-guide plate 12a. The glass substrate 2a is mounted on the perimetric stop base 101a, allowing the glass substrate 2a in connection with the diffusion sheet 15a, the prism sheet 16a, the light-guide plate 12a, the lighting member 13a and the reflective sheet 14a to be arranged opposite the perimetric stop base 101a. 
However, during assembly of the conventional backlight module 1a, a step of turning over the upper frame 10a is required, and it is thus obvious that the assembly process is not smooth. Furthermore, the lower frame 11a and the upper frame 10a are arranged with a mutual securing engagement structure. After the lower frame 11a is engaged and secured with the upper frame 10a, it is difficult to disassemble, which is disadvantageous to the improvement of production efficiency. If there is any need for maintenance and repair or if replacement of the diffusion sheet 15a or the prism sheet 16a becomes necessary, the rework process is bothersome to operators and the products are prone to damage. Therefore, some hazards of low product yield may occur while the structure is disadvantageous and could result in disfigurement or damage. The above-mentioned product damage includes scores and scratches on the diffusion sheet 15a, the prism sheet 16a, the light-guide plate 12a and the reflective sheet 14a, which adversely affect the overall brilliancy, thus reducing the value of the products. Moreover, depending on different design requirements, the quantity of the diffusion sheets 15a and the prism sheets 16a may not be the same, and neither the assembling sequence of the diffusion sheets 15a and the prism sheets 16a to be assembled is. In the event that a polarizing sheet, an intensifier sheet and other members are added for purpose of adaptation of further optical characteristic, and it is desired to perform a test process to verify the members are assembled in the right sequence and registered properly, similar problems occur during said test process. Dissassembly of the engaged lower frame 11a and upper frame 10a is difficult, and the products are potentially damaged during disassembly and reassembly of the members. Additionally, in the assembled structure of the conventional backlight module 1a, the stop base 101a is arranged over the optical films; thus the upward and even light output obtained from the effect of those optical films is subject to reduced light output area due to blocking by the stop base 101a. The conventional backlight module 1a is unable to be made more economically.
Accordingly, this invention is provided to remove the above disadvantages with a reasonable design.